1. Field of the Invention
The invention relates to cutting inserts used in metalworking operations, and more particularly, is directed to a cutting insert having distinct edges each capable of machining in a different profile.
2. Description of the Related Art
In metalworking operations it is typical to utilize a cutting insert mounted within a toolholder, whereby that cutting insert is dedicated to cutting a workpiece to impart a particular profile. However, machining a workpiece to a finished product oftentimes requires many distinct operations using many different types of cutting inserts separately engaged with the workpiece wherein each insert has a different cutting profile. As an example, threading the inner wall of a cylinder would typically require a first pass with a roughing tool to insure the inner diameter is concentric and to remove any voids that may have been generated during the fabrication of the workpiece. A cutting insert of this type would have a blunt edge which engages a relatively large width of the workpiece.
After this step, a second machining operation utilizing a threading insert is required. However, the roughing insert must now be removed from the toolholder, and the threading insert introduced. To do this, the spindle turning the workpiece would have to be stopped and the toolholder partially disassembled to remove one insert and to insert another, thereby producing downtime in which the machining tool is not active. To be efficient, it is necessary to utilize the tool as much as possible, and to minimize such downtime.
Another manner in which the same operation might be performed would involve the use of two separate toolholders, whereby one toolholder has an insert suitable for roughing, while a second toolholder has an insert suitable for threading. Each of these toolholders could be introduced to the workpiece either separately or simultaneously. However, this requires the use of two toolholders and furthermore, such an arrangement consumes twice the space that would be consumed by a single toolholder. This is an inefficient use of space, and furthermore, the simultaneous use of two toolholders may be impossible when the bore of the workpiece is so small that only a single toolholder may fit within it.
A design is needed to eliminate the necessity of changing cutting inserts during a metal working operation, or introducing a second toolholder during a metal cutting operation in order to accomplish a specific task. Furthermore, a design is needed that would eliminate the need to change one insert within a toolholder with another insert when the use of a single toolholder is the only option available to a machinist.
U.S. Pat. No. 4,880,339 entitled xe2x80x9cDrill Bar With A Cutting Insertxe2x80x9d illustrates a single cutting insert having two opposing edges protruding from the toolholder such that a workpiece may be engaged by either of these edges depending upon the position of the toolholder. However, the two opposing cutting edges of this insert are identical to one another, such that multiple metal working operations are not possible.
U.S. Pat. No. 1,926,531 entitled xe2x80x9cMultiple Tool And Holderxe2x80x9d is directed to an insert having three distinct cutting regions radially positioned at approximately equal angles to one another such that each of these cutting regions may be positioned to engage the workpiece. However, this nonconventional arrangement requires the cutting insert to be repositioned for each cutting operation desired. Furthermore, the cutting edges of each of these cutting regions face the same upward direction thereby restricting the versatility of the insert. In particular, such a cutting insert would not be useful for the linear side-to-side motion available on the spindle of many machine tools.
In one embodiment of the subject invention, a cutting insert is comprised of:
a) an insert body having at least one pair of cutting regions;
b) wherein each cutting region is comprised of a cutting edge;
c) wherein each of the cutting edges in a pair is diametrically opposed about a pair axis; and
e) wherein at least one pair of cutting regions has two cutting edges with cutting profiles that are not identical to one another.
In another embodiment, a toolholder assembly is comprised of:
a) a tool holder having an outer profile;
b) a cutting insert mounted within the toolholder, wherein the insert is comprised of:
1) an insert body having at lest one pair of cutting regions;
2) wherein each of the cutting regions in a pair is diametrically opposed about a pair axis;
c) wherein each cutting region is comprised of a cutting edge;
d) wherein the cutting edges of each pair of regions face a single rotary direction along a pair circle about the pair axis and extend beyond the outer profile of the toolholder; and
e) wherein at least one pair of cutting regions has two cutting edges with cutting profiles that are not identical to one another.